In recent years, technology regarding a battery used in portable terminals has developed rapidly, retaining the electric capacity of a battery at a relatively high level and reducing the size of a battery, so that a variety of optional functions can also be provided to the portable terminals. For example, portable terminals include a file reproduction function that can play back stored audio files and video files. The portable terminals also include various additional functions, such as a camera function for taking a still picture, and a video camera function for tracking and shooting a moving object.
However, although the battery has been developed to greatly increase its electric capacity, the various functions of the portable terminals consume energy from the battery at a higher rate for a shorter period of time.
Meanwhile, a battery mounted in a portable terminal is charged in such a way that the portable terminal is directly connected to an adapter or placed in a holder connected to an adapter. In that case, when the battery is charged to more than a certain ratio of the total charge capacity, the portable terminal recognizes that the battery has been completely charged and then indicates the charged state. Thereafter, the portable terminals disconnect the electric power supply to the battery.
In general, batteries undergo a natural discharge as time elapses. If a battery is not used for a relatively long time period from the time when the battery has been completely charged, the battery does not remain in a fully charged state. Therefore, if a user does not use a battery for a certain period of time after it was completely charged, the user must use the battery that already has been discharged by a certain amount of capacity.